A model of oxygen-activity-dependent adsorption (desorption) to metal-oxide interfaces

Non-reactive metal-oxide interfaces are thermodynamically stable over an extended range of oxygen activity and temperature. It is supposed that, at each point of this range, the interface adopts a (slightly) different equilibrium structure and chemistry due to variations in the local composition of the interface by Gibbs' adsorption. The quality and quantity of adsorbed species at the interface, chemical bonding across the metal-oxide interface and related properties, such as adhesion for example, should then vary with the external parameters, temperature and chemical potential of the components. A physico-chemical continuum model is developed that applies point defect chemistry to transition metaloxide interfaces. It predicts specific interfacial energies through Gibbs' adsorption isotherms as a function of component chemical potentials. Experimental results obtained for MgO-Cu interfaces are reviewed and compared with the model's results. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.